In the above-described technical field, patent literature 1 discloses a technique of suppressing, in a vehicle, noise that has come from outside the car and mixed with speech in the car. In patent literature 1, the outside-car noise is suppressed using an adaptive filter based on the output signal of a microphone that picks up the in-car speech and the output signal of a microphone that picks up the outside-car noise. In addition, patent literature 2 discloses a technique of clearly collecting a remote sound by combining sound collection using a parabolic reflector and sound collection using an ultra-directional microphone.